In a large bowl, combine the flour, baking powder and salt. In a mixing bowl, cream butter and sugar. Add eggs, milk and vanilla; mix well. Stir in dry ingredients just until moistened. Fold in frozen blueberries.
Fill greased or paper-lined muffin cups two-thirds full. Combine sugar and nutmeg; sprinkle over muffins. Bake at 375 degrees F or 190 degrees C for 20-25 minutes or until muffins test done. Cool in pan for 10 minutes before removing to a wire rack.